<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>监听器应用-距离转换器</title>
</head>
<body>
    <script>
        var vm=new Vue({
            el:'#app',
            data:{
                km:0,
                m:0
            },
            methods:{
                kmtom:function(val){
                    this.m=this.km*1000;
                },
                mtokm:function(val){
                    this.km=this.m/1000;
                }
            },
            watch:{
                km:'kmtom',
                m:'mtokm'
            }
        })
    </script>
</body>
</html>